Many systems need multi-channel receivers. For example, Data Over Cable Service Interface Specification (DOCSIS) system introduces in the DOCSIS 3.0 specification the concept of bonding several physical channels in order to provide higher data rates. This channel bonding represents a technique for logically combining multiple DOCSIS channels, wherein in DOCSIS 3.0 four channels are bonded.
As can be seen in FIG. 1a, data 105 may be split between several Radio Frequency (RF) channels 111, 112, 113, 114 at the transmitter (TX) 110, wherein each channel is modulated on an own carrier frequency in the frequency spectrum 120. Furthermore, for instance, several other signals may be transmitted via separate channels in the spectrum 120.
In the receiver (RX) 150, the multiple channels 111, 112, 113, 114 are received by means of separate single channel tuners 141, 142, 143, and the data transmitted via the multiple channels 111, 112, 113, 114 is recombined after being processed by backend units 151, 152, 153, 154. Thus, the data rate can be increased without changing the existing infrastructure, i.e. with respect to DOCSIS, the existing cable can be used.
The system partitioning depicted in FIG. 1a shows the disadvantage that several single-channel receiver ICs 141, 142, 143, 144 are necessary in order to receive the multiple channels 111, 112, 113, 114, thereby increasing costs and power consumption.
One more integrated solution represents the use of a wideband receiver IC 160, as exemplarily depicted in FIG. 1b. In this case, cable operators have a restriction: the 4 bonded channels are required to be located in a limited RF bandwidth. For instance, in DOCSIS 3.0 four channels 111′, 112′, 113′, 114′, transmitted from TX 110′, are located in 60 MHz/100 MHz RF bandwidth 115′.
Cable is a media that is used for several application like Internet, television (TV), Voice over IP (VoiP) and others. General trend in home is to use Set-Top-Boxes for video (TV, Video on Demand, etc.) and Cable Modems for Internet and VoiP.
Therefore, DOCSIS 3.0 typical location is in the Cable Modem, and wideband receivers 160, as exemplarily depicted in FIG. 1b, are candidates for these Cable Modems. The wide band receiver 160 comprises a wideband tuner 161 and a wideband backend 162.
When wideband receivers are very well suited for Internet needs, they are also very inefficient for receiving single-channel services where low power is required. As an example, VoiP must be able to operate on battery.